Typewriter ribbon is normally wound on a core to produce a ribbon spool for use in a typewriter. One method of producing the individual typewriter ribbon spools includes the severing of a sheet of typewriter ribbon into a plurality of ribbons and attaching each ribbon to a spool core mounted for rotation on a take-up shaft. As the core is rotated, the ribbon is wound onto the core to form a spool of typewriter ribbon.
As the sheet of ribbon is divided into a plurality of ribbon strips, each strip is connected to one of the spool cores mounted on the take-up shaft so that a plurality of spools of ribbon are formed simultaneously. To eliminate problems resulting from differences between each of the spool cores and the ribbon wound thereon, the spool cores are not keyed to the shaft. Rather, each spool core is separated by a spacer which is keyed to the take-up shaft but slidable along the longitudinal length of the shaft. By applying an inwardly directed load to the endmost spacers, a desired friction is generated between the spacers and the typewriter ribbon cores so that the ribbon cores are driven by their engagement with the spacers keyed to the take-up shaft. In this way, a constant load may be applied to each of the ribbon cores with the cores being allowed to slip relative to the driving shaft when the load on the ribbon exceeds a predetermined limit. In this way, irregularities are avoided in the typewriter ribbon as it is wound onto the cores.
In prior art systems, the ribbon cores have normally had a circular aperture therethrough. In the ribbon take-up structure, a cylindrical shaft has been employed with a longitudinal keyway formed therein to accept a key extending interiorly from a spacer having a corresponding cylindrical aperture therethrough. The spacers are mounted on the shaft with the typewriter ribbon spool cores engaged onto the circular shaft separated by the spacers.
Because the typewriter ribbon spool cores have, in some circumstances, been formed with cylindrical apertures therethrough, accommodation of the cores in the above-described system has required no more than the mounting of the cores on the take-up shaft with spacers mounted therebetween. However, because the typewriter ribbon cores must have an aperture formed therethrough to mate with the particular typewriter mechanism on which the typewriter ribbon is to be mounted, the aperture in the core is not always cylindrical. Therefore, where the aperture in the typewriter ribbon core is irregular, as opposed to being cylindrical, the use of the typewriter ribbon take-up structure described above has not been usable, and the advantages of the system permitting a constant angular rotation driving torque for each of a plurality of typewriter ribbon spools on a single driven shaft is lost. Therefore, a need has arisen for a system to drive a plurality of typewriter ribbon spool cores while maintaining a constant angular torque on each spool core and permitting the independent slippage of each core relative to the drive shaft when the maximum drive torque is exceeded.